Segment information - Summary of Activity by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 30, 2016	Aug. 01, 2015	Jul. 30, 2016	Aug. 01, 2015	Jan. 30, 2016
Segment Reporting Information [Line Items]
Sales	$ 1,373.4	$ 1,410.6	$ 2,952.3	$ 2,941.2
Operating income (loss)	119.9	100.8	331.9	277.0
Total assets	6,298.0	6,071.3	6,298.0	6,071.3	$ 6,464.9
Sterling Jewelers
Segment Reporting Information [Line Items]
Sales	839.4	858.5	1,819.8	1,802.7
Operating income (loss)	140.9	157.8	339.2	336.0
Total assets	3,699.5	3,445.7	3,699.5	3,445.7	3,788.0
Zale Jewelry
Segment Reporting Information [Line Items]
Sales	331.0	336.4	712.4	709.3
Operating income (loss)	0.5	(2.0)	18.8	8.4
Total assets	1,931.1	1,864.0	1,931.1	1,864.0	1,955.1
Piercing Pagoda
Segment Reporting Information [Line Items]
Sales	57.0	52.9	126.0	117.1
Operating income (loss)	(0.2)	(0.1)	7.6	5.0
Total assets	138.4	116.9	138.4	116.9	141.8
UK Jewelry
Segment Reporting Information [Line Items]
Sales	145.2	159.1	289.2	305.6
Operating income (loss)	1.7	3.2	3.0	3.7
Total assets	392.3	432.2	392.3	432.2	427.8
Other
Segment Reporting Information [Line Items]
Sales	0.8	3.7	4.9	6.5
Operating income (loss)	(23.0)	(58.1)	(36.7)	(76.1)
Total assets	$ 136.7	$ 212.5	$ 136.7	$ 212.5	$ 152.2